Voluntary feed intake and feeding behaviour of group-housed growing pigs are affected by ambient temperature and body weight

Abstract

The effect of ambient temperature on individual feeding behaviour was studied in six groups of Piétrain×Large White barrows. In experiment 1 (two groups), ambient temperature varied in a cyclic way from 22 to 12°C and 12 to 22°C with three or four consecutive days at each of the following temperatures: 22, 19, 16, 14 or 12°C. Similarly, in experiment 2 (two groups), temperature varied from 19 to 29°C and 29 to 19°C with three or four consecutive days at 19, 22, 25, 27 or 29°C. In both experiments, each group was used over two successive cycles with an initial body weight (BW) of 37 kg at cycle 1 (four pigs per group) and 63 kg at cycle 2 (three pigs per group). During experiment 3, groups of four pigs were exposed to varying temperatures over one cycle either as in experiment 1 (one group) or as in experiment 2 (one group); their initial BW was 45 kg. Photoperiod was fixed to 12 h of light. In experiments 1 and 2, neither the daily number of meals (11) nor the rate of feed intake (37 g/min) were affected by temperature. The daily number of meals was lower at cycle 2 (9 vs. 12 at cycle 1 on average) but their size was higher (305 vs. 181 g/meal at cycle 1). The feeding pattern was mainly diurnal (62%). From individual data obtained at each temperature level and each stage of growth in this study ( N=296), an equation to predict the voluntary feed intake (VFI) from temperature ( T, ranging between 12 and 29°C) and body weight (BW, ranging between 30 and 90 kg) is proposed: VFI (g/d)=−1264+117 T−2.40 T 2+73.6BW−0.26BW 2−0.95 T×BW (RSD=329). The present relationship indicates that VFI depends on temperature and body weight with a marked negative effect of high ambient temperatures in heavier pigs.